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Home Material Sciences Diamond Polycrystal Nanocomposit

Diamond Polycrystal Nanocomposit

Description

At present one of the most important line in solving the problem of the development of superhard materials with qualitatively and quantitatively new complex of physico-mechanical properties is the use of nanodispersed materials as the initial ones. Under the adequate conditions a unique complex of mechanical properties, e.g., a combination of very high hardness and fracture toughness, can be realized in a nanodispersed polycrystal.

In the development of production technologies of novel superhard materials using initial nanomaterials, the retention of the material nanodispersed state in the course of sintering is an important problem. In addition, one should remember that mechanical properties are highly structure-sensitive, which is particularly distinct in using nanomaterials.

In the present paper developed conditions of preparative treatment of diamond nanopowders, and their effective compacting, including at heightened temperature, before a sintering, are presented. Effect of prior compacting conditions on process of obtaining of qualitative polycrystals by sintering is studied. Thermobaric conditions of production of polycrystal materials based on diamond powders of nanometric range are investigated and optimized. The obtained results have allowed to develop optimum conditions of production of tool materials based on the diamond nanopowders

Innovative Aspect and Main Advantages

It is experimentally proved that the most efficient approach to the improvement of physico-mechanical properties of diamond polycrystals produced from nanopowders is a search for the optimal conditions of sintering of mixtures containing additions acting as solvents for carbon (Co, Ni, Fe, alloys of them, etc.) and as inhibiters of the grain growth and the mixture should be mechanically activated.

The use of high-pressure technique in combination with purification and vacuum degassing for sintering of statically synthesized diamond nanopowders with an initial particle size of about 100 nm favors the formation of nanostructure elements of 10 to 50 nm in size in a polycrystal due to fragmentation of coarser initial grains, wich is supported by TEM studies. The using of the preactivation of the initial statically synthesized diamond nanopowders using cold isostatic pressing has allowed the production of polycrystals with a density of 3.31 g/cm3,Vickers hardness of 35.4 GPa (P = 9.8 N) and fracture toughness K1c = 6.8 MPa.m1/2.

Areas of Application

Tools made of the composites of statically synthesized diamond nanopowder can successfully compete with single-crystal natural diamond tools. The composites may be used for making variously purposed cutting, deforming or measuring tools and thanks to high fracture toughness, the composites may be used as inserts in drilling tools. Now the samples of the instrument are tested in construction.


Fig. 1 The typical electron-microscopic image particle structures
of the polycrystal from nanodiamond by static syntheses

Fig. 2 Cutting plates, drawing die and cutting tool

Stage of Development

Prototype available for testing

Contact Details

Shulzhenko Aleksandr Aleksandrovich
V. N. Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine
2 Avtozavodaskaya Str., Kiev, 04074, Ukraine
Tel.+380 44 4303506
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
www.ism.kiev.ua

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